Some bulk containers are made of a flexible plastic material such that they may be collapsed and folded when empty to facilitate storing and shipping them. These bulk containers may typically contain a ton or more of material and may be formed as a bag of a woven fabric material or, if a waterproof container is desired, the bag or a complementary liner may be formed from a plastic sheet such as a polyethylene or polypropylene film typically having a thickness between 4 to 10 mils. Previous such bulk containers, such as disclosed in U.S. Pat. No. 5,104,236 have been formed from a tubular blank of material and may be formed without any scrap and are very useful, durable and reliable in use.
However, certain materials are not available in tubular form and cannot easily be formed into a tubular blank without damaging the material. Examples of such materials are metallized materials such as various metallic foils, nylon, Ethylene-vinyl-alcohol (EVOH), or a metallized saran or polyvinylidene chloride or vinylidene copolymer film commonly sold under the trade name Saranex.RTM., from the Dow Chemical Company. The metallized saran or other foils or films can be weak and if placed over a folding board or the like to form a tubular blank, the board may crease and damage the metal foil or film. Typically, to provide reinforcement for such materials, they are coextruded with a polyethylene or polypropylene film as the outer layer and the saran or other material as the inner layer to provide a liquid-tight barrier layer. Thus, to maintain the integrity of the bag or liner it is imperative that the inner, barrier layer not be damaged, breached or broken during manufacture and assembly of the bag.